1. Field of the Invention
The present invention relates to a device for preventing error or misreading in a marine compass fastened to a sloping surface, the compass being provided with a pendulum (9) mounted for limited pivoting movement inside its spherical casing (1), the pendulum having rotatably and pivotably mounted on it a compass disk (16) wich a scale (18), which is intended to be read against a so-called steering line (12) on the pendulum (9) at an angle of 0.degree. to about 45.degree. relative the horizontal plane.
2. Description of the Prior Art
Marine compasses which include a pendulum provided with steering lines, the pendulum being pivotably mounted in the spherical casing and having pivotably and rotatably mounted on it a compass disk provided with a scale, intended to be read against the steering lines, are already known, e.g. from the marine compass type K-121 marketed by SILVA, Sweden AB, Sollentuna, Sweden.
Each of these known compasses is intended for mounting on a vertical bulkhead in a boat for reading from the side, and if this is done the observer should be able to read correct values on the scale, independent of the heeling of the boat. However, if the compass is mounted on a bulkhead sloping forwards or backwards relative the fore-and-aft line (which many bulkheads do) and adapter blocks are not used to ensure that the compass assumes a vertical position when it is fitted, incorrect values will be read from the scale as soon as the boat heels (rolls) a small amount, which is due to the axis about which the pendulum swings being displaced from the point about which the compass disk is pivotably and rotatably mounted on the pendulum.
To remedy this problem it is of course possible to select a compass which has full gimbal suspension of the device carrying the compass disk, but such a compass cannot be used if it is to be observed from the side (at an angle of 0.degree.-45.degree. relative the horizontal plane) since at least one of the gimbal rings, irrespective of whether it is placed inside or outside compass casing, and irrespective of how the compass is fitted and how much the boat heels, will always be situated between the observer and the scale of the compass disk, which makes correct reading of the scale more difficult, and sometimes impossible.